A tube pump configured such that a flexible tube is disposed in a ring-shape along a cylindrical inner wall surface formed on a housing and fluid in the tube is transported by rotating a roller along the inner wall surface while letting the roller press the tube between the roller and the inner wall surface of the housing is known (see Japanese Patent Provisional Publication No. 2011-102574A (hereafter, referred to as patent document 1)).
Since, in the tube pump of this type, a particular portion of the tube is bent by 180 degrees repeatedly, a large degree of deformation is caused locally at the particular portion of the tube, and thereby fatigue rapidly progresses. Therefore, life of the tube is relatively short in comparison with other components, such as a pump, and the tube needs to be replaced periodically as a consumable article.
Furthermore, in the tube pump, a sucking process (i.e., a process transferring from a state where a hollow part of the tube serving as an operation chamber is pressed and an cross sectional area of the hollow part becomes the minimum to a natural state where the cross sectional area of the hollow part of the tube becomes the maximum) is performed by an elastic restoring force of the tube itself. Therefore, the speed of the sucking process is low, which causes limiting the rotational speed of the pump.
U.S. Patent Application Publication No. 2012/0020822 A1 (hereafter, referred to as patent document 2) describes a pump including: a cylindrical inner wall, a cylindrical diaphragm forming a ring-shaped operation chamber between the diaphragm and the inner wall surface, a presser roller deposed to rotate along the inner wall surface while pressing the operation chamber, a ring-shaped actuator disposed between the diaphragm and the presser roller, and a support member restricting the distance between the actuator and the inner wall surface within a predetermined value.
Since, in the pump described in the patent document 2, an elastic member (diaphragm) is not pressed in a state where the elastic member is bend by 180 degrees as in the case of the above described tube pump, the local deterioration of the elastic member is suppressed. Furthermore, in the pump described in the patent document 2, the actuator which is thicker than the diaphragm is disposed between the diaphragm and the presser roller, deterioration of the diaphragm is suppressed.